Management of older persons living with HIV (PLWH) (? 50 years old) is becoming increasingly more complex as a majority is greater than 50 years old. Attempts to improve the quality of life of older PLWH using adjunctive therapeutics to combination antiretroviral therapy (cART) have largely been unsuccessful. While the impact of physical activity on brain health (assessed by neuropsychological performance and neuroimaging) has been well studied in older healthy HIV uninfected (HIV-) individuals and neurodegenerative conditions, few studies have concentrated on older PLWH. Both clinically and pathophysiologically, HIV associated neurocognitive disorders (HAND) differs from other neurodegenerative disorders seen with aging (e.g. Alzheimer's disease (AD). A positive association relationship between exercise and cognition has been observed in PLWH, but physical activity has been primarily examined using self-report questionnaires that are subjective and not quantitative. To date, no study has focused on the direct effects of exercise on neuropsychological performance or neuroimaging in PLWH. The objective of this proposal is to conduct a prospective controlled intervention trial to determine if an increase in physical activity through a monitored aerobic and resistance exercise (EXS) program improves brain health in older PLWH. We will quantify physical function (physical activity using cardiorespiratory capacity and actigraphy) and brain function [neuropsychological performance testing and neuroimaging (cerebral blood flow (CBF) and brain volume)] in older physically inactive PLWH at baseline and 26 weeks after randomization to either an EXS or a social-interaction stretching (SIS) program. In addition, we will obtain serum markers of neurogenesis, glucose regulation, and systemic inflammation. Our specific aims include: Specific Aim 1. Examine the effects of exercise on cognitive function in older PLWH. Specific Aim 2. Examine the effects of exercise on brain structural/functional measures in older PLWH. Secondary endpoints of this proposal will identify implementation factors needed to scale up an EXS program in older PLWH to HIV clinics at multiple institutions. Key barriers and facilitators will b analyzed from qualitative data obtained from questionnaires, focus groups, and in-depth interviews of shareholders. A direct impact of these expected outcomes will be the adoption of a more physically active lifestyle by older PLWH and improved EXS guidelines and programs for older PLWH.